1. Technical Field
This invention relates to multi-functional apparatuses for controlling various functions or accessories of a motor vehicle, and more specifically to a multi-functional apparatus incorporating a flexible clutch which allows the apparatus to operate in the event one portion of the apparatus, such as a windshield wiper drive shaft, becomes immovable.
2. Discussion
Almost all automotive vehicles in present day use employ some form of window wiper assembly for cleaning the front and/or rear windows of the vehicle. With a rear window wiper assembly, typically a wiper blade is mounted upon a bracket which is coupled to a wiper arm. The wiper arm is attached to a wiper shaft rotatably driven in a cyclical oscillating manner by a helical gear. A reversible, fractional horsepower, direct-current electric motor serves to actuate the helical gear through an armature shaft-mounted worm gear and enmeshed therewith. This type of rear window wiper arrangement is usually mounted upon a pivoting lift gate of a mini-van, station wagon, sport-utility vehicle or the like. One such example is disclosed in U.S. Pat. No. 5,519,258 entitled xe2x80x9cSystem and Method for Controlling Vehicle Lift Gate Window Wiperxe2x80x9d, which issued to Stroven et al on May 21, 1996, the disclosure of which is hereby incorporated by reference.
It is also common in the automotive industry to employ windshield and rear window wiper systems that have an electric motor and a worm gear. The electric motor constantly reverses direction in order to oscillate a wiper arm and wiper blade back and forth within a wiping range or a path on the window. In other words, the electric motor and worm gear rotate in first respective directions for moving the wiper arm and the blade to one side of the window and then reverse directions for moving the wiper arm and blade to the other side of the window. In some situations, the electric motor and worm gear are further rotated to move the wiper arm on and off of the window to a park position.
Still further, it is known to provide a four-bar linkage to couple a worm gear to a window wiper shaft. In this arrangement, an electric motor and worm gear rotate in a unidirectional manner to facilitate back and forth oscillation of a window wiper arm and blade. In this unidirectional, four-bar linkage construction, a pin always moves concurrently with the worm gear, since the pin is always fixed to the worm gear in a single location. The pin is also coupled to the four-bar linkage.
Typically, various other functions are also performed by the motor and assembly which drives the window wiper arm. Many present day vehicles incorporate a rear window release lock or latch. This lock or latch is actuated by a solenoid and can be unlocked to allow for upward pivotal movement of a rear window in relation to the otherwise stationary lift gate. In combination therewith, a separate lift gate lock is also often mounted upon the lift gate door for fastening the lift gate to the body thereby preventing inadvertent pivotal opening. This lift gate lock is traditionally operated by a manual key or handle rotation, or through a separate electric motor or solenoid.
A potential problem can arise with the above-described arrangements if the wiper arm becomes frozen to the windshield such as because of ice. In this instance, the output shaft of the electric motor, which is operationally coupled to the windshield wiper drive shaft, is prevented from rotating because the windshield wiper drive shaft has become locked up or otherwise immovable. Thus, the various other functions performed by the motor, such as controlling operation of the window release lock or latch or the lift gate lock will not be possible. Accordingly, there is a need for some form of arrangement which allows the windshield wiper drive shaft to be disengaged or xe2x80x9cde-clutchedxe2x80x9d from the output shaft of the drive motor in the event the windshield wiper blade of the vehicle becomes frozen to the vehicle window or temporarily immovable for any other reason.
The above functions and objects are performed by a multi-functional apparatus incorporating a flexible clutch in accordance with preferred embodiments of the present invention. One preferred embodiment incorporates a coil spring which is disposed within a gear, which is operatively driven by the motor of the apparatus. The spring is also disposed over a drive shaft which is operably associated with a windshield wiper of the motor vehicle. The inside diameter of the coil spring is larger than the diameter of the drive shaft such that a definite clearance exists therebetween. The spring is positively coupled to the gear and to the drive shaft and acts as a means for transmitting the driving force imparted by the gear to the drive shaft.
The spring, being flexible, enables the gear to be rotated relative to the drive shaft in the event the wiper of the vehicle becomes frozen to the window of the vehicle or otherwise immobilized temporarily. This is permitted by the clearance between the spring and the driveshaft. The clearance allows the spring to be xe2x80x9cwound downxe2x80x9d on the drive shaft as the motor rotates, thereby allowing for rotation between the gear and drive shaft. Thus, since the motor output shaft is still allowed to rotate, the various other functions performed by the apparatus are not impeded should the wiper blade become stuck to the window for any reason.
In an alternative embodiment, the spring is disposed within an intermediate wiper spur gear and a drive shaft associated with the wiper spur gear. In an alternative preferred embodiment, permanent magnets are disposed on a wiper gear of the apparatus and on an intermediate wiper spur gear to effect a magnetic coupling therebetween. Should the wiper drive shaft positively coupled to the wiper gear become temporarily immobilized, such as if the wiper freezes to the window of the vehicle, the magnetic coupling between the two gears can be overridden by the motor of the apparatus.
In yet another alternative preferred embodiment one or more cables are used to couple a wiper gear and a wiper spur gear. At least one of the cables is flexible. If a drive shaft coupled to the wiper gear becomes immobilized for any reason, at least a limited degree of rotational movement of the wiper spur gear is possible by a motor of the apparatus through the flexible cable coupling these two gears.